OBSTETRICS PEER-REVIEWED

Uterine anomalies
in pregnancy
Clinical pearls for assessment and management of the pregnant
patient with a uterovaginal anomaly
by ANNE-MARIE AMIES OELSCHLAGER, MD

U
terine anomalies are asso- into the distal vagina and urethra.
ciated with higher rates of Resorption anomalies represent per- ASRM MÜLLERIAN
pregnancy complications, sistence of the longitudinal uterine or ANOMALIES
including spontaneous vaginal septum. Transverse anomalies CLASSIFICATION 2021
abortion, ectopic pregnancy, preterm include obstructing vaginal septa or
labor, malpresentation, and abruption. cervical atresia.
Obstetricians should understand the Diagnosis
embryology, incidence, classifications, Classification and diagnosis To differentiate uterine anomalies,
and management of patients with of uterovaginal anomalies imaging or direct visual examination
uterine anomalies during pregnancy. The American Society for Reproductive of the contour of external uterus and the
Medicine (ASRM) Müllerian Anomalies endometrial cavity is required. To dif-
Embryology Classification (MAC) system, updated ferentiate the bicornuate from septate
The process of uterine and vaginal in 2021, 1 categorizes the range of from arcuate uterus, ideally, a line can
development begins in the first anomalies by descriptive terms and be drawn from cornua to cornua. If the
trimester. The bilateral müllerian includes müllerian agenesis, cervical external contour indents more than
(paramesonephric) ducts develop into agenesis, unicornuate uterus, uterus 10 mm, the uterus is bicornuate. If there
the uterus, fallopian tubes, cervix, and didelphys, bicornuate uterus, septate is less than 10-mm external contour
proximal vagina. These ducts fuse and uterus, longitudinal vaginal septum, indentation and less than a 10-mm
internal canalization of each duct will transverse vaginal septum, and complex fundal cavitary indentation with the
produce 2 channels divided by longitu- anomalies. An online interactive clas- leading angle of the indentation greater
dinal septum. The septum will typically sification is available online. To view than 90°, the diagnosis is arcuate uterus.
resorb throughout the second trimester. the ASRM MAC 2021 online, please scan If the indentation extends more than
The urogenital sinus will also separate the QR code. 10 mm into the cavity and the leading

ANNE-MARIE AMIES OELSCHLAGER, MD, is a professor of obstetrics and gynecology and specializes in pediatric
and adolescent gynecology at the University of Washington School of Medicine in Seattle. Her clinical expertise is in congenital
uterovaginal anomalies and differences of sex development.

10 CONTEMPOR ARYOBGYN.NE T December 2022

 OBSTETRICS
PEER-REVIEWED

angle is less than 90°, the diagnosis is The incidence of preterm birth before
septate uterus. 37 weeks is approximately 40% for
Optimal tests include 3D transvaginal patients with known uterine anoma-
ultrasound, MRI, saline sonohysterog- lies. The highest risk of preterm labor
raphy, or laparoscopy or laparotomy is associated with uterine didelphys
combined with hysteroscopy or hys- (56%), unicornuate uterus (43%), bicor-
terosalpingogram (HSG; Figures 1 nuate uterus (39%), and septate uterus
and 2).2,3 Less sensitive diagnostic tests (31%).12 Congenital uterine anomalies
include 2D transvaginal ultrasound, are also associated with increased
clinical assessment at cesarean section, risk of first and second trimester loss,
as well as hysteroscopy or HSG without cervical insufficiency, premature
external uterine contour evaluation.4 rupture of membranes, fetal malpre-
A pregnancy will alter the contour of sentation, fetal growth restriction,
the uterine fundus and repeat imaging placental abruption, placenta previa,
after resolution of the pregnancy is more FIGURE 1. MRI images allow visual- retained placenta, and cesarean birth
ization of the patent and nonpatent
likely to result in an accurate diagnosis. uterine anatomy. This image is
(Table).13-15 For this reason, consultation
diagnostic for a left unicornuate with a maternal-fetal medicine special-
Incidence and uterus with patent vagina (out- ist during pregnancy is recommended.
associated anomalies lined arrow) and a functional right
Studies using optimal imaging have noncontiguous uterine horn (solid Management
arrow).2,3 (Image courtesy of
identified uterine anomalies in Anne-Marie Amies Oelschlager, MD.)
of obstetric risk
5.5% to 9.8% of the general population, in Limited data suggest that cervical length
16.7% of those with recurrent miscar- screening for short cervix (< 25 mm)
riage, and in 24.5% of those with a and fetal fibronectin screening may
history of miscarriage and infertility.5-8 be useful for predicting preterm birth
A study of uterine evaluation during in those with septate uteri. The data
cesarean sections noted that 5% were have not shown a consistent predic-
found to have a uterine anomaly: tive benefit for those with unicornuate,
71.0% were septate uteri, 19.4% were didelphic, or bicornuate uteri.16,17
bicornuate uteri, 6.4% were unicornuate Most studies of 17-hydroxyprogester-
uteri, and 3.2% were didelphic uteri.4 one caproate (17-OHPC) for prevention
Anorectal, cardiac, limb, ear, skeletal, of premature birth did not include those
and especially renal anomalies have with a history of congenital uterine
all been commonly associated with FIGURE 2. A complete septate uterus. anomalies. In a small retrospective cohort
müllerian anomalies. Obstetricians The arrow points to the septum at study of 48 women with congenital
should have a low threshold to consider the level of the internal os of the uterine anomalies, there was an equally
cervix. The septum extends into
renal imaging, as they may be present in high rate of recurrent preterm birth in
the cervix. Note that the lead-
30% of those with fusion anomalies.9,10 ing angle of the septum in the those who received 17-OHPC and those
endometrial cavity is less than 90°, who did not. 17-OHPC has not been
Obstetric complications and there is a flat external fundal demonstrated to prolong pregnancy in
Arcuate uterus is the most common contour.2,3 (Image courtesy of women with uterine malformations or
Anne-Marie Amies Oelschlager, MD.)
anomaly identified, but it does not prenatal diethylstilbestrol exposure.18
appear to be associated with a higher Patients with a history of cervical
rate of infertility or miscarriage by variant; however, the remaining uter- atresia may have had reconstructive
prospective studies.5,11 In general, the ine anomalies confer a significantly surgery to create a patent cervix. In those
arcuate uterus is considered a benign higher risk of obstetric complications. who can become pregnant, case reports

December 2022 CONTEMPOR ARY OB/GYN ® 11

 OBSTETRICS
PEER-REVIEWED

have suggested that abdominal cerclage If a longitudinal vaginal septum

with planned cesarean delivery is war- TABLE. Risk of Obstetric is identified during a pregnancy, the
ranted.19 There are limited data to suggest Complication for Those With septum can be resected prior to labor
Identified Uterine Anomalies
that cerclage may decrease the rate of in the operating room or during the first
vs Those Without Identified
preterm delivery in those with bicornu- Uterine Anomalies13-15 stage or early second stage of labor prior
ate uteri with cervical incompetence.20 to pushing. Clamping and resecting the
Historically, hysteroscopic uterine Obstetric outcome Odds ratio intervening septal tissue should be done
septum resection has been recom- First trimester loss 1.8 with extreme care to avoid the bowel,
mended for those with a history of urethra, and the cervices. Use of the
Second trimester loss 2.9
recurrent pregnancy loss, preterm labor, LigaSure device (Medtronic) has also
and infertility.21 In case control studies, Placenta previa 4.0-5.8 been described.26 After vaginal delivery,
hysteroscopic metroplasty has been IUGR 1.5-3.8 the vagina should be carefully inspect-
associated with a higher live birth rate ed, hemostasis assured, and gaps in
IUFD 1.6
and lower spontaneous abortion rate but the mucosa should be reapproximated
has also been associated with higher rates Abruption 1.9-5.2 using absorbable suture.27
of preterm delivery, cesarean section, PTD < 34 weeks 4.9 Many patients with obstructive
and fetal malpresentation compared uterovaginal anomalies will present in
PTD < 37 weeks 3.0-3.9
with those with uterine septum who did adolescence or prior to puberty. Some
not have surgery.22,23 A multinational PPROM 2.5-3.0 patients may have had vaginal septum
multicenter trial randomly assigned 80 Cervical insufficiency 15.1 resection for a transverse vaginal septum
women with a septate uterus to septum or may have had a vaginal pull-through
Fetal malpresentation 7.9-11.1
resection or expectant management. Live procedure for distal vaginal atresia.
births occurred in 31% who had septum Cesarean delivery 2.1-13.5 Interposition vaginal grafts, including
resection compared with 35% who Retained placenta 1.7
buccal mucosa or bowel grafts, may have
did not have surgery.24 It appears that been used to bridge the gap between
IUFD, intrauterine fetal demise; IUGR,
uterine septum resection may benefit intrauterine growth restriction; PPROM,
the upper and lower vagina. In these
select patients with recurrent fetal loss, preterm premature rupture of membrane; situations where interposition grafts
PTD, preterm delivery.
but their risk of obstetric complications or residual septal tissue is present, and
is still significantly elevated. If the septum there is a concern for vaginal obstruction,
extends into the cervix, resection of the significantly higher, likely because of a planned cesarean delivery is recom-
cervical component has not been typi- combination of higher rates of abrup- mended. Additionally, for those who
cally recommended due to concern for an tion, preterm labor, and malpresenta- have had anorectal malformations with
increased risk of cervical incompetence. tion. The risks of abruption and failure a history of anoplasty or reconstructive
of external cephalic version (ECV) urological procedures where continence
Delivery considerations may be higher in patients with uterine may be negatively impacted by vaginal
The incidence of cesarean delivery anomalies; however, there have been delivery, planned cesarean delivery
in those with uterine anomalies is case reports of successful ECV.25 should be offered. For any patient with

Uterine anomalies are found in laparotomy combined with hysteroscopy retained placenta, and cesarean birth.
approximately 5% to 10% of the general or hysterosalpingogram. Consultation with a maternal-fetal
CLINICAL population. One in 8 with recurrent medicine specialist is recommended
PEARLS Congenital uterine anomalies
miscarriage and 1 in 4 of those with a during pregnancy.
are associated with increased risk
history of miscarriage and infertility have
of first and second trimester loss, Ultrasound guidance is recommended
uterine anomalies.
preterm labor, cervical insufficiency, for management of first and second
Optimal diagnostic tests include 3D premature rupture of membranes, fetal trimester therapeutic and incomplete
transvaginal ultrasound, MRI, saline malpresentation, fetal growth restriction, abortion, as well as for removal of
sonohysterography, laparoscopy or placental abruption, placenta previa, retained placenta.

12 CONTEMPOR ARYOBGYN.NE T December 2022

 OBSTETRICS

Pregnancy-related homicides are

a uterovaginal anomaly, aberrant urologic anat-
omy, including pelvic kidneys and ectopic and
leading cause of maternal death
duplicate ureters, are common. Obstetricians by LINDSEY CARR, EDITOR state-level firearms legislation and
should be vigilant during operative deliveries gun ownership, and the plethora
to avoid injury to the urinary system. Women in the United States of loopholes allowing access
Obstetricians should be prepared for an are more likely to be murdered to remain.
increased rate of retained placenta after vaginal during pregnancy or soon after The recent decisions regard-
delivery in patients with uterine anomalies. childbirth than to die from the ing women’s reproductive
Ultrasound-guided management of instru- country’s top 3 leading causes of rights in the United States place
mentation during removal of retained placental maternal death—high blood pres- further emphasis on these
tissue is recommended. sure disorders, hemorrhage, or issues, Lawn and her colleagues
sepsis—according to research in said. Specifically, reproductive
Management of therapeutic and the BMJ. Most of these pregnancy- coercion is a common aspect of
spontaneous abortion related homicides result from a intimate partner violence and
For those with 2 cervices, a history of vaginal combination of intimate partner increases the risk of unwanted
septum resection, or long interposition vaginal violence and firearms, according pregnancy. Restricting access to
grafts, uterine evacuation can be challeng- to Rebecca Lawn, PhD, of Harvard abortion care further endangers
ing, with increased difficulty visualizing and TH Chan School of Public Health, women, as unwanted pregnan-
dilating 1 or both cervices. For those with a and colleagues. cies can often amplify risks in
uterine septum, bicornuate uterus, or uterine They argue that society must abusive relationships.
didelphys, care must be taken to avoid inad- address “male violence,” or the Lawn and her colleagues point-
vertent instrumentation of the wrong cervix violence committed by men, ed out that pregnancy typically
and uterine horn. For those with congenital to save the lives of hundreds of means more contact with health
reproductive tract anomalies, procedures women in the United States every care providers, which can provide
should be performed with ultrasound guid- year. Although intimate partner opportunities for screening and
ance.28 Operative hysteroscopy may facilitate violence is common worldwide, other approaches to help women
guided entry into the cavity if dilation with with 1 in 3 women reporting at risk of intimate partner violence.
ultrasound guidance alone is not success- experiences of physical, sexual, or These interventions from doctors
ful.29 Although rare, there are case reports of psychological abuse/violence by and health care teams may help
ectopic pregnancies occurring in asymmetric a partner in their lifetime, rates in stop a pattern of abuse that could
or noncommunicating uterine horns. MRI the United States are significantly eventually lead to homicide or
may be useful if a pregnancy is visualized by higher than rates in other high- other negative health outcomes,
ultrasound but is not accessible through uter- income countries. the authors said.
ine instrumentation and cannot be visualized The homicides committed by All causes of maternal mortal-
through hysteroscopy.30 an intimate partner in the United ity are important, the authors
States are overwhelmingly tied to said, but the tragedy here is that
Conclusion firearms, and homicides related pregnancy-associated homicide
Uterine anomalies are common in the general to pregnancy are no different. is preventable. They concluded
population and are associated with a higher risk Recent reports found that firearms with an emphasis on the need to
of obstetric complications. Optimal imaging is were used in 68% of pregnancy- end male violence, including gun
recommended for accurate diagnoses. Consul- related homicides between violence, for the health and safety
tation with a maternal-fetal medicine specialist 2008 and 2019, with Black women of women everywhere. 
is recommended during pregnancy.  at a substantially higher risk of REFERENCE
murder than White or Hispanic 1. Lawn RB, Koenen KC. Homicide is
a leading cause of death for pregnant
FOR REFERENCES VISIT women. These domestic homi- women in US. BMJ. 2022;379:o2499.
cides are also associated with doi:10.1136/bmj.o2499
contemporaryobgyn.net/Uterine-anomalies

December 2022 CONTEMPOR ARY OB/GYN ® 13